LED lighting market is growing very fast and becoming more and more important. For the AC input source, most LED drivers adopt switching mode power supply (SMPS) based on flyback topology. The flyback SMPS circuit usually consists of AC input, PWM control circuit, transformer and constant voltage/current control circuit, wherein the output voltage/current control circuit are coupled through an optical coupling element to the primary side PWM control circuit. The PWM control circuit adjusts the switching duty cycle when line voltage or load is changed, so constant output current or voltage can be realized.
However, the cost of flyback SMPS circuit is relatively high and the total system size is big. For home appliance, it is ideal that the LED lighting driver is compact and can be placed in the lamp holder like CFL (compact fluorescent lamp). Thus the whole LED lighting system's installation will be easy. Also for compact LED lighting driver, isolating may not be needed if plastic lamp holder is used.
Therefore, it is necessary to provide new cost down solutions with less component count, small print circuit board size and better price/performance ratio.